Thus far, a thin film transistor for which amorphous silicon, polycrystalline silicon or the like has been used as a driving transistor for electronic devices. However, amorphous silicon or polycrystalline silicon does not have optical transparency and has light sensitivity in the visible light range, and therefore a light-blocking film is required. Therefore, in a case in which the thin film transistors are present on the front side of displaying elements when viewed from the display observation side, the visibility of display is affected. Therefore, the thin film transistors were disposed on the rear side of the displaying elements.
For the colorization of reflective display apparatuses such as reflective liquid crystal display apparatuses or electrophoretic display apparatuses, color filters are generally used. Here, for the above-described reason, display apparatuses for which color filters are used have a structure in which a liquid crystal-encapsulating layer or an electrophoretic particle layer is formed between the color filters and the thin film transistors. However, when the color filters and the thin film transistors are formed at the above-described location, for example, in a case in which the liquid crystal-encapsulating layer is used, it is necessary to align the thin film transistors and the color filters after encapsulating liquid crystals. Therefore, it is difficult to obtain high accuracy, and cost rise or yield reduction results.
Therefore, it is attempted to facilitate the aligning of the color filters and the thin film transistors by forming thin film transistors having optical transparency on the color filters. In this case, since the thin film transistors have optical transparency, it is possible to dispose the thin film transistors on the front side of displaying elements when viewed from the display observation side, and the produced display has a structure in which images are visible through the thin film transistors having optical transparency (see NPL 1).
Here, for semiconductor layers in the thin film transistors having optical transparency, for example, indium gallium zinc oxide or the like is frequently used (see NPL 2).
In addition, for gate electrodes or capacitor, electrodes in thin film transistors having optical transparency, for example, indium tin oxide (ITO) or the like is frequently used.
In addition, for gate insulating layers in thin film transistors, for example, silicon nitride films formed using chemical vapor deposition (CVD) or the like is frequently used. In a case in which a silicon nitride film or the like is formed using CVD, it is common to carry out a surface treatment using H2 plasma as means for cleaning the substrate, and then to form the film using reactive gas such as SiH4 or the like.